3:30 PM - 5:00 PM
[PPS05-P16] Carbon dioxide sequestration on Earth and Mars: Potential of carbonates derived from Samail Ophiolite as analogues for Martian atmosphere-hydrosphere interactions
Keywords:ALH84001 Meteorite, Carbonate Minerals, CO2 Sequestration, Mars, Oman Ophiolite, Serpentinization
According to a recent estimate, atmospheric CO2 accounts for ~80% of the C-budget in Ca-rich carbonates from Oman [4]. Mars has had a thicker atmosphere since the Noachian era (3.9 Ga), due to Tharsis volcanic activity injecting huge amounts of SO2 [7], with greater CO2 buildup than the modern Martian atmosphere. As a result of cloud formation followed by acidic rain, sulfate-rich (40%) sediments were abundantly formed [8]. The Noachian atmosphere could have been lost to space as a result of a combination of impact erosion and sputtering [9]. The residual CO2 began to form carbonates in dust and soil [10], and trace amounts were also found in Martian meteorites [11]. Discovery of phyllosilicates [12] suggest that the H2O on Mars was not acidic until the Tharsis formation. We attempted to estimate the Martian atmospheric CO2 input in Ca-rich carbonates (age = 3.9 Ga; [13]) in ALH84001 (4.1 Ga; [14]). Distinct carbonate populations have been found in ALH84001 using sequential acid extraction and microprobe analysis [6].
The Martian atmospheric CO2 contribution in Ca-rich carbonates in ALH84001 is calculated using a 2-tracer and 3-component mixing model [15]. The end members, such as Noachian CO2 [16], water [17, 18], Fe-Mg-rich carbonates [6], and weathered carbonates [6], are used in the 3-component mixing model (see Image1). Our calculations show that the Ca-rich carbonates in ALH84001 received half of their C-budget (48 ± 16%) from atmospheric CO2, assuming that they formed after the formation of Fe-Mg-rich carbonates during an aqueous event in early Martian history. Other sources (e.g., DIC) account for the remaining 52 ± 14% of the C-budget in ALH84001 Ca-rich carbonates.
Martian meteorites and terrestrial analogues are useful resources for studying Martian surface and subsurface processes until the samples returned to Earth by a mission linked to the Perseverance rover [19]. The carbonates in ALH84001 [6, 17] and Samail Ophiolite [20, 21] are chemically and isotopically distinct, implying that the latter could be a useful Mars analogue [22]. A detailed examination of these carbonate types (particularly listwaenite) will help us understand the evolution of Martian atmosphere-hydrosphere interactions.
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